The present invention relates to a multiconductor electrical cable connector and, more particularly, to IDC (insulation displacement crimp) connector assemblies for a flat ribbon-like multiconductor electrical cable.
Since individual manual connection of each conductor in a multiconductor electrical cable, which usually has more than three conductors and as many as eighty or more conductors therein, would be a difficult and tedious task. Therefore, a number of specialized connectors have been developed for simultaneously connecting each of the plural conductors to those of another multiconductor electrical cable via another connector, for example, to a plural signal input terminal of a computer or the like, to conductive paths on a printed circuit board or the like, etc. Typically, these specialized connectors include multiple housing parts between which the cable is clamped, and usually before or during that clamping the multiple contacts of the connector puncture the electrical insulation of the cable to connect with respective conductors therein. The housing parts are mechanically secured in clamping engagement with the cable, and strain relief is usually provided by the clamping strength and/or by the terminal parts of the contacts pierced through the cable insulation.
From the U.S. Pat. No. 4,824,394 an IDC connector with rotated conductor pairs and strain relief base molded onto cable is known. The IDC connector is formed by a cable termination assembly that comprises a generally flat electrical insulation. The cable has got a longitudinal extent and a planar extent. At least one pair of said conductors include connecting portions rotated relative to each other about an axis generally parallel to the longitudinal extent of the cable and aligned with respect to one another in a direction generally perpendicular to the planar extent of the cable. The conductors of said pair include an area of rotation where said conductors are so rotated. At least two electrical contacts each include terminal means for connecting with the connecting portion of a respective one of said pair of conductors and connecting means for connecting with an external electrically conductive member and a strain relief body is molded directly to said cable including the area of rotation of said pair of conductors.
The U.S. Pat. No. 4,030,799 shows a multiconductor electrical cable termination. The multiconductor electrical cable termination is formed as an integral structural combination of the multiconductor electrical cable, the plurality of electrical contacts, and a housing part that is molded about at least a portion of each of the contacts and a portion of the cable. Each contact forms a junction with a respective conductor of the cable, and the integral housing part is molded under elevated temperature and pressure conditions so that each of the junctions is substantially fully encapsulated by at least one of the cable insulation and the molded body part and, thus, maintained relatively free of moisture and oxygen. The terminal portion of each electrical contact preferably extends fully through the cable insulation, and openings provided in the molded housing part offer access to the ends of those terminal portions for test probing thereof. Furthermore, the terminal portion of each electrical contact is in the same plane and is offset with respect to the contacting portion thereof. The electrical contacts are arranged in a forward row and a rearward row. In the forward row they have their terminal portions offset to the left with respect to their contacting portions, and in the rearward row they have their terminal portions offset to the right with respect to the contacting portions. This offset configuration of the electrical contacts allows them to be of reasonable size and strength while the contacting portion of each electrical contact in one row is directly aligned with the contacting portion of an opposite electrical contact in the other row and with each of the relatively closely positioned parallel conductors being connected to only a single respective electrical contact.
In computer systems there is an increasing need for cables and connectors providing a high bandwidth and a high count of signal lines. Flat ribbon cables provide a high count of signal lines having a suitable high frequency behavior. Therefore, more and more flat ribbon cables are employed in such high frequency environments, e.g., as a connection for system-level interfacing between a computer and devices including hard disks, floppy disks, CD-ROM, printers and scanners, such as the high density 50 pin SCSI (Small Computer System Interface) 2 cable/connector. In order to improve the high frequency behavior of the cable, shieldings are provided to protect the electrical signals being transmitted through the cable from electromagnetic interference.
The noise caused in a cable can further be reduced by only using every other conductor in a flat ribbon cable to transmit a signal. The remaining conductors are functioning as ground lines in order to further shield the signal lines from each other. Hence, two adjacent conductors never carry signal lines, instead, signal lines and ground lines alternate, e.g., ground-signal-ground-signal and so on. However, reaching the connector most of the effort spend to improve the high frequency behavior is lost, since the cross talk of the available connectors are too high for a use in a high frequency environment.
Starting from this, the object of the present invention is to provide a cable connector assembly having an improved high frequency behavior, i.e., a cable connector assembly having a low noise characteristic.
According to the present invention a cable connector assembly for being connected to a flat ribbon cable containing a plurality of conductors is provided. The cable connector assembly comprises a plurality of electrical contacts arranged in a first row and a second row, whereby the arrangement of the electrical contacts forms an orthogonal grid. Assuming said plurality of conductors being consecutively numbered 1 to N, said electrical contacts being arranged in a way that an electrical contact associated to an odd numbered conductor has got adjacent electrical contacts in the same row and an electrical contact at the same position in the other row that each are associated to even numbered conductors.
In other words, the electrical contacts are being arranged in a way that the electrical contact associated to one conductor is spaced further apart to the electrical contact associated to the respective next but one neighboring conductor, so that cross talk is reduced when having every other conductor assigned to a signal line and the remaining conductors to ground lines.
Hence, according to the present invention a cable connector assembly for being connected to a flat ribbon cable including a plurality of conductors and electrical insulation about said conductors maintaining the latter electrically insulated from each other. The cable connector assembly comprises a plurality of electrical contacts, each including terminal means being configured to connect at least one of said conductors directly through said electrical insulation to form an electrical junction, and contacting means on each of said electrical contacts being configured to electrically connect each of said electrical contacts to an external member. It further comprises a housing for holding said contacting means arranged in a first row and a second row forming an orthogonal grid. Assuming the plurality of conductors being consecutively numbered 1 to N, said electrical contacts being formed so that such terminal means being associated with odd-numbered conductors being respectively connected with every other contacting means of said first row and every other contacting means of the second row, being offset by one, whereby such arrangement causes each conductor being space further apart to its next but one neighboring conductor so that cross talk is reduced when having every other conductor assigned to a signal line and the remaining conductors to ground lines.
The advantage is that a good high frequency behavior is provided by just providing in average one ground line per signal line and having maximum separation of signal lines from each other in the connector itself.
Furthermore, the present invention allows to use flat ribbon cables in areas in which up to know only more expensive cables could be used, such as coax cable, but the invention may not be a substitute for coax cables in general. The costs may be significantly reduced for a respective connection.
Advantageously, a connector in accordance with the present invention still meets the form requirements set by the International Electromechanical Commission (IEC), i.e., it is still form fit compatible, while providing a significantly improved crosstalk behavior between adjacent signal lines.